15:40
Turbo expanders III
Chair: Dr. Rene Pecnik
15:40
20 mins
|
NUMERICAL PREDICTION OF PERFORMANCE OF 75-kWe RADIAL TURBINE FOR OTEC APPLICATION
Nithesh K.G, Dhiman Chatterjee
Abstract: Extended Abstract
|
16:00
20 mins
|
NUMERICAL STUDY OF MULTISTAGE TRANSCRITICAL ORC AXIAL TURBINES
Luca Sciacovelli, Paola Cinnella
Abstract: Many studies have demonstrated that supercritical ORCs, i.e., ORCs in which heat is supplied at a pressure greater than the liquid/vapor critical point pressure, have an even greater potential, since they allow better recovery efficiency for a simplified cycle architecture . The selection of the most suitable working fluid is of crucial importance in designing an ORC process, since it requires to take into account thermodynamic, environmental and safety aspects.
In this work, we numerically investigate the performance of three axial, multi-stage, ORC turbines. All of them were designed for low-temperature heat recovery purposes. In two cases, the working fluids are the refrigerants R134a and R245fa. Both supercritical and subcritical inlet conditions are considered. A fully supercritical carbon dioxide (CO$_2$) turbine is also studied for comparison.
|
16:20
20 mins
|
AERODYNAMICS OF CENTRIFUGAL TURBINE CASCADES
Giacomo Persico, Matteo Pini, Vincenzo Dossena, Paolo Gaetani
Abstract: The centrifugal turbine architecture represents a promising solution for Organic Rankine Cycle (ORC) Systems, in the small-to-medium power range. A centrifugal machine can better accomplish the high volumetric expansion ratios typical of ORC applications, and allows for assembling a multiplicity of stages in a relatively compact machine
A preliminary design exercise proposed by the authors has recently shown the potential of a transonic multistage centrifugal turbine for medium power applications (about 1 MWel). The achieved promising features, however, also depend on the correlations used in the preliminary procedure, and must be assessed with high-fidelity computational methods such CFD.
In the present work the aerodynamics and performance of centrifugal turbine cascades are studied by applying a three-dimensional CFD model. The study is focused on a transonic centrifugal turbine stage, designed by applying simple but effective design concepts. The behavior of the stage is analyzed focusing first on the profile aerodynamics, considering both stator and rotor blade rows. Finally the morphology
of secondary flows and the three-dimensional effects of the channel flaring are investigated.
|
16:40
20 mins
|
DESIGN AND PERFORMANCE ESTIMATION OF RADIAL INFLOW TURBINES COUPLED WITH A THERMODYNAMIC CYCLE ANALYSIS PROCEDURE
Carlos André de Miranda Ventura, Andrew Stewart Rowlands
Abstract: In this study, the integration between a comprehensive preliminary design and performance estimation approach for radial inflow turbines and a thermodynamic cycle analysis procedure is described.
The integration involved the creation of a MySQL database capable of accommodating and sorting large amounts of data and resulted in the creation of a model-based radial inflow turbine database for a range of Organic Rankine Cycle (ORC) conditions that employed a variety of working fluids.
This integrated methodology provides a more comprehensive approach in the estimation of the overall performance of ORCs because unlike conventional methods, which typically assume a value for the efficiency of the turbomachinery used in the cycle, here we use a validated preliminary design model to calculate efficiency estimations for a given cycle condition.
Our database permitted the establishment of several model-based correlations with regards to the use of these turbines and cycles by determining relations between cycle performance (specific energy production from a hot resource, B (kJ/kg)) and typical operating point constraints, such as the resource fluid temperature and high-side pressure.
In the present work, results for a variety of working fluids and ranges of operating conditions are tested and discussed.
|
|
